So you didn't expect this version of the Happy Tree Friends? Believe it or not, the Fandom has transformed the little, cute, colorful critters into really popular anime characters, giving them depth and creating a lot of fan stories involving them.
Many can be seen here: Happy Tree Friends (you still have to make an account to see all the portrayals). Those who have a pixiv-account can find even more under the "HTF", "HTF擬人化" (Basically "HTF Humanization") and "ハピツリ" ("Hapitsuri") tags. The characters are human and more developed than the actual, canon characters, though there is no possible way to join all the interpretations of a character into one.
Note: This is only a large fanon creation, there is not an actual, official anime.
The most common themes or conceptions portrayed in the anime styled fanstories or fanart are:
And others see it as her and Flippy's evil daughter, who took the looks after her mother and her father's insanity. This is most probably due to a really popular artist who created some pictures with the potentialspawnofFlippy and Flaky.
Perpetual Frowner: Handy. Mostly due to the fact that he's frustrated because he is an amputee.
Plucky Comic Relief: Splendid appears sometimes in Flippy / Flaky serious comics and wrecks the mood. Nutty too, but he appears less often than Splendid.
Red Oni, Blue Oni: Nutty and Sniffles. Splendont and Splendid are an inverted example color-wise, because, personality-wise, Splendid is the hot blooded, enthusiastic of the two, while Splendont appears stoic or deadpan most of the time.
Shown Their Work: It's easy to brush fans off as only liking the art style or the characters, but much of the art proves how faithfully they watch the show. An excellent example is this very page image, which depicts characters in notable scenes throughout the series.
Wife Husbandry: There are many side-stories in which Flaky is under Flippy's care as a little kid or she befriends him when she's still a child, only to fall in love with him later. One example is here.